How to Think Like Sherlock Holmes

My first real introduction the famous consulting detective, Sherlock Holmes, was in English class at the age of 15 with Sir Arthur Conan Doyle’s The Speckled Band. This was followed quickly by The Adventure of the Yellow Face and A Case of Identity.

I was one of the few who were completely enthralled with the detective and have maintained my interest in his methods ever since.

In 2004, Sherlock Holmes (or his skills and attitude) were revived in the form of Dr. Gregory House. Not only does House show the same deductive powers, often diagnosing patients at a glance, but he also has his trusty confidant Dr. Wilson and displays a strong belief in his own intellectual superiority. To top it off, House lives at apartment 221B.

More recently, the excellent BBC series Sherlock was broadcast in July 2009. This modern retelling featured Benedict Cumberbatch as Sherlock Holmes and Martin Freeman as Dr. John Watson. The film Sherlock Holmes featuring Robert Downey Jr. and Jude Law followed 6 months after.

With the recent reintroduction of Sherlock Holmes into modern culture, more people than ever want to know How to Think Like Sherlock Holmes.

The quick wits and sharp observational skills of Sherlock Holmes are nothing short of legendary and even though he often expresses a need for his investigations to stick with facts, he would often display a remarkable reliance on his intuition. It was obvious to him that logic and intuition played an equal part in solving the mysteries presented to him.

Here are the qualities you need to hone if you want to think more like the great detective:

Intuition

Observation

Listening

Logic

Humility

Open-Mindedness

Develop Your Intuition

There is an evolutionary advantage for being able to spot at a glance who is friends with whom and what a person’s emotional state is. Intuition can be developed by practice and perseverance. Although it isn’t possible to use intuition to solve everything, there are times where listening to our intuition is a useful technique. When drawing conclusions about more “human” things; relationships, connections with others and emotions intuition can be extremely helpful.

Daniel Kahneman’s international bestseller, Thinking Fast and Slow, deals heavily with intuition and is a great primer on the subject.

The book focuses on the 2 states of thinking, which Kahneman labels as systems. System 1 (intuition) is rapid, instinctive and based on emotion. System 2 is slow, deliberate and more logical.

Holmes summarised his intuition like this:

It was easier to know it than to explain why I know it. If you were asked to prove that two and two made four, you might find some difficulty, and yet you are quite sure of the fact.

Interestingly a large number of people who think of themselves as “logical” thinkers generally prefer system 2. These types of people are generally reliant on facts and evidence, but are quick to dismiss intuition and gut-feelings as unscientific and unreliable. System 1 can be in this situation be referred to as intuition.

Intuition is developed through years of practice and experience with a subject until the knowledge has been internalised, similar to learning to drive a car. We all have instinctual feelings and thoughts based on previous experiences we’ve had. Most of this is unconscious and the reason behind a particular feeling or hunch is not easily explained. Malcolm Gladwell’s book, Blink: The Power of Thinking Without Thinking, highlights how quickly our brains are able to take in multiple stimuli and in milliseconds come to a conclusion before we’ve consciously examined the situation.

In his book Mastery, Robert Greene explains how after intense focus in a discipline (the 10,000 hour rule popularised in Malcolm Gladwell’s Outliers) a person’s brain is physically altered, to the point where instinct and intuition opens up a whole new level of thought. With enough study a person can reach a level where what used to take hours of consideration can be achieved in mere seconds as a feeling or hunch. Sherlock’s great skill can be attributed to his intense focus on the study of people and circumstances.

Eventually his study would have hit a tipping point where his intuition kicks in and takes over. Holmes summed this up when he stated: “From long habit the train of thoughts ran so swiftly through my mind that I arrived at the conclusion without being conscious of intermediate steps”. This happened in an instant and with no effort required from Holmes, which helps to explain why he is so surprised and disappointed that everyone doesn’t see the world the way he does.

Intuition can be a powerful decision-making process if used in conjunction with the facts and evidence available. Almost everyone has made a decision based on a gut-feeling and often the outcomes of these decisions are positive and in some cases, life-saving.

A good way to look at intuition is as an “educated counsellor”. It is our subconscious that powers intuition and the subconscious has access to all our experience and observations (from being born to right now). Our subconscious can see patterns and connections long before we even realise, these connections often manifest in the form of “a gut-feeling.” Although intuition cannot alone be relied upon as the sole source of decision-making information, when your hunches and gut-feelings are cross-referenced with the facts, startling conclusions can be drawn.

Learn to deduce facts from studying a person

Just by watching a person, it is sometimes possible to learn how they are feeling. Some people are naturally more skilled at this, most women are better than men for evolutionary reasons. Anyone can learn to be a skilled people-watcher with the right practice:

Try people watching. Spending some time every day simply watching people as they go about their day. Good observation can tell you a great deal about a person’s habits, mannerisms and personality. Although there is a lot of guesswork involved in people watching (deliberately, because that’s what makes it fun), you can also try to hone your guesses down to identifying specific behavioural traits and mannerisms that can serve as future reference for you. Zoologist Desmond Morriss wrote a fantastic book on the subject – Peoplewatching.

Improve your power of observation

Possibly the most remarkable ability Sherlock Holmes possessed, was his observation of things that other people missed; he often stated “You see, but you do not observe.”

Being observant is about slowing down and taking the time to look at the small details which are often overlooked. Increasingly, people rush around, spend little time observing and make assumptions based on obvious things, without considering the fine details.

You can increase your powers of observation using several methods, each of which requires practice:

Focus on improving your sight, smell, and sound, the most commonly used senses. Because we are so used to using these senses, we often take them for granted and make assumptions about what they perceive. Fine tune and refine these 3 main senses, before focusing on touch and taste. Highly-attuned senses will give you a greater variety of information to consider.

Learn to discriminate against details that have no value. Focus on details that are relevant and significant “It is the highest importance in the art of detection to be able to recognize out of a number of facts, which are incidental and which are vital.” However, make sure not to ignore the smallest details, Holmes makes it clear that “The little things are infinitely the most important.”

Practice with spotting style puzzles. Puzzles that ask you to find the difference between different images, puzzles that ask you to find hidden words and images, and puzzles that require you to navigate through mazes are all ways of honing your observation powers. Practice these frequently and time yourself to find things faster and faster without panicking.

Quick quiz yourself and start learning to pay more observational attention to your surroundings. An example of such observations “Think of your grandparents’ house. Is it a two-floored house? If so, how many steps are there? How many bedrooms? Which floors are the bedrooms on? How many beds are there in the house? Which rooms are the beds in?” If you don’t know, you see, but don’t observe; in short, teach yourself to take in all the detail you can.

Additionally, if you can stay calm and think clearly under pressured, you already have an advantage over others.

Be a Better Listener

Most of us don’t listen because we are too arrogant, selfish, lazy, preoccupied or think we are sure what the speaker is trying to say.

Listening is an art and its importance can never be overestimated. Sherlock Holmes was a master artist. When a person you’re speaking to recalls everything you’ve said to them, you feel like either they possess an incredible memory or they care a great deal. Either assumption has good results for the listener.

What can sometimes seem like a great feat of magic is often a result of a great combination of concentration, courtesy and memory.

A good listener will hear not only the words that the person is saying, but the meaning behind them and also the meaning behind what is not said. For many reasons, politeness, social pressure etc. people often disguise their true meaning in metaphor or simply omit the message altogether. What is left out often holds more details that what is verbalised.

Never underestimate anyone. People often assume that their thoughts are more connected and complex than others. Holmes was quick to recognise and acknowledge the complexity of others –

A complex mind. All great criminals have that.

Never try to over simplify the motivations of another person and give credit to where it is due.

A lot of good information can come from “simple” sources e.g. magazines, tabloids, gossip. Do not let your ego get the better of you. Such simple sources are a gateway to how the majority of people think. Sherlock Holmes was an avid reader of Agony Aunt columns in the paper and clearly used this as a source of information about how people tick! Soak up and consider everything and don’t be an intellectual snob or you’ll be throwing away a great deal of usable information.

Understand How to Read a Situation:

See. What is happening?

Observe. What do you notice that is different; a stain, a crease?

Deduce. What does this imply?

Use Logic

Simple defined, logic is the study of valid reasoning. Logic is drastically underused and combined with fine observation and skilled listening, will allow you to gather information and come to accurate conclusions.

As mentioned earlier, intuition is incredibly useful but should always be supported by logic and factual analysis. Sometimes, just going with your gut feeling and ignoring facts will lead to mere speculation.

Holmes advised

It is a capital mistake to theorise before you have all the evidence. It biases the judgement

Pay attention to his warning and be sure to apply evidence to your theories.

For example: You observe stain in your friend’s shirt. What kind of stain is it? Food? Logically that means he’s careless. What? You know for sure that he’s very tidy and neat? Then logically he was in a hurry to get out of the house. Why? Is he on time for every class or meeting? Of course he is, since he’s very tidy and neat, so what happened? Maybe he overslept. So you go to him or her and ask, “Did you oversleep today?” If you’re right, have fun with the reaction! So, the train of thought is: stain – food – he’s tidy – hurrying – oversleep.

Analyse Situations Using a Step-by-Step Process

Holmes was good at a process of elimination, a process by which he would dispose of the unlikely, the illogical, the uncertain, and cut narrow theories to reach what he believed to be the only logical conclusion.

When you have eliminated the impossible, whatever remains, however improbable, must be the truth.

The process used goes like this:

Twist theories to suit facts and instead of facts to suit theories. Use established, measurable and proven facts to develop your theory. If the facts mean that parts of your theory are no longer suitable, discard that part of the theory. If you ignore the fact and persevere with you existing theory, you will inevitably come to a false conclusion.

How did they do what they did? E.g. How did the he enter the building without leaving a trace? How did she manage to move the box on her own? How did she get to the meeting first even though she doesn’t drive?

As mentioned, keep working on the details; most people, be they criminals, detectives, or the average person, do not observe all the details and this is how they are caught or found out.

Go through who, when, what, where, and why facts.

Holmes’s straightforward principles largely follow:

“If ‘P’, then Q’.”

‘P’ is observed evidence and ‘Q’ is what the evidence indicates.

But there are also, midway steps. In “A Scandal in Bohemia” Holmes deduces that Watson had got very wet lately and that he had “a most clumsy and careless servant girl”. When Watson asks how Holmes knows this, Holmes answers:

It is simplicity itself … My eyes tell me that on the inside of your left shoe, just where the firelight strikes it, the leather is scored by six almost parallel cuts. Obviously they have been caused by someone who has very carelessly scraped round the edges of the sole in order to remove crusted mud from it. Hence, you see, my double deduction that you had been out in vile weather, and that you had a particularly malignant boot-slitting specimen of the London slavery.

In this case, Holmes used several connected ideas:

If leather on the side of a shoe is scored by several parallel cuts, it was caused by someone who scraped around the edges of the sole in order to remove crusted mud.

If a London doctor’s shoes are scraped to remove crusted mud, the person who so scraped them is the doctor’s servant girl.

If someone cuts a shoe while scraping it to remove encrusted mud, that person is clumsy and careless.

If someone’s shoes had encrusted mud on them, then they are likely to have been worn by him in the rain, when it is likely he became very wet.

By applying such principles in an obvious way), Holmes is able to infer from his observation that if P – “the sides of Watson’s shoes are scored by several parallel cuts” then Q – “Watson’s servant girl is clumsy and careless” and “Watson has been very wet lately and has been out in vile weather”.

This method is however, not infallible. At the end of “The Adventure of the Yellow Face”, Holmes tells Watson;

If it should ever strike you that I am getting a little over-confident in my powers, or giving less pains to a case than it deserves, kindly whisper ‘Norbury’ in my ear, and I shall be infinitely obliged to you.

As with everything, never use one method or piece of evidence in isolation.

Humility

Humility is an attractive quality in anyone and if you master deductive reasoning, jealousy will surround you, so don’t brag about your methods. The common cliché “A magician never reveals his secrets” fits wonderfully into this scenario.

In ”A Study in Scarlet”, Holmes explained “You know a conjurer gets no credit when once he has explained his trick; and if I show you too much of my method of working, you will come to the conclusion that I am a very ordinary individual after all.”

Sherlock didn’t believe that knowing the methods of his deduction brought benefit to anyone. In fact, he understood that revealing the manner of his deduction would dispel the effectiveness and entertainment of what he did.

Walk a Friend/Colleague Through Your Conclusions

This practice is another feature that Holmes and Dr. House have in common. Holmes has Watson and House has Wilson (even their names are similar!)

Both Dr. House and Sherlock Holmes trusted only a few people, and only once they have proved their trustworthiness and loyalty.

Nothing clears up a case so much as stating it to another person. Make sure you talk through your conclusions with someone you trust. Dr. House would use both Wilson and his “team” to bounce ideas off of each other.

In almost every case, some irrelevant phrase spoken by one these trusted people would trigger a thought which would lead to the right conclusion, or diagnosis in Dr. House’s case.

Keep an Open Mind

It may be that talking your theory through with another person will spark new ideas that can be incorporated into your conclusion or may even replace your original theory. It’s also possible that another person may disagree with your inferences and proposes a different equally logical theory.

While it may seem that what you see before is incredibly simple and clear, appearances can be deceiving. Sherlock Holmes was well aware of this and used it to his advantage in unscrambling a myriad of possibilities which cannot be explained solely by what you can see and hear.

Holmes knew to balanced intuition with logic, he drew conclusions from details and he listened carefully.

Yet, he also kept an open mind, and accepted that some possibilities may yet be unexplained

Life is infinitely stranger than anything which the mind of man could invent.

Some things exist that are difficult to explain and it pays to open to all manner of possibility in this scenario (e.g. the existent of one or more deities).

Make Sure You Have Fun

One of the key factors people tend to forget when trying to solve a problem or come up with an idea, is to STOP thinking about it. Holmes worked incredibly hard when investigating, but he understood the important of leisure and relaxation. Often, Sherlock would take Watson to an opera half-way through an investigation. When you relax, your subconscious begins to whir away behind the scenes, creating connections between your subject of study and other aspects of your knowledge and experience. This is why some of the greatest ideas can come in the shower or when going for a walk. Constantly thinking and pushing your intuition can be exhausting, so taking time to recover is essential to ensure you can remain sharp and focused.

Key Points

Observing body language is a great way to learn more about a situation, but 20% of the time body language will be misleading. Trust it too much and you’ll likely make some big mistakes.

Don’t rush into making decisions before you’ve considered all available evidence. Reflect on the facts multiple times. Fast decisions often come from instinct and past experience or training. Give yourself plenty of time to analyse all the facts and come to a conclusion.

Don’t share your ideas until you are a 99% sure you’re right. If you end up making an odd prediction based only on intuition and no evidence and the situation ends up being completely different, you may be seen as unreliable and too quick to judge

Most importantly, try not to overlook anything, no matter how small. Also ALWAYS use a combination of evidence, intuition and logic to come to a conclusion. Never rely on a sole source of information or an isolated method.

Further Reading

If you want to learn more about thinking like Sherlock Holmes, these 3 books are probably the best next steps you can take:

A truly spectacular article breaking down the art of deduction into its simplest form; I have wrote and read many blogs on the subject but none have explained intuition as well as you have. also I want to thank you for the lesson in humility, often times I think that I shouldn’t have to read things such as magazines (for sake of example) because things like that seemed irrelevant, thank you for reminding me to be humble.